Chelsea will play Seattle Sounders in a friendly on July 18, according to Emerald City Supporters, a Sounders supporters group.
No official statement has been made by Chelsea or Seattle Sounders, the newest team to Major League Soccer, but EPL Talk has a message in to the Sounders to confirm or deny the story received confirmation from a Seattle Sounders representative that the story is true.
The MLS Rumors website, meanwhile, is reporting that Sounders ticket representatives have been telling fans about the upcoming match, which will be played at Qwest Stadium.
For the most comprehensive list of preseason friendlies around the world involving Premier League teams, visit our Premier League Preseason Friendlies page.
Thanks to Jeff Hash for the tip.
Update (as of February 17, 2009): The Seattle Sounders finally officially confirmed that the game will take place. Kickoff time will be noon PT. Tickets will be available for sale sometime in the Spring. Capacity will be limited to approximately 24,500. Note that tickets will be available to season ticket holders first (which, so far, number 19,500). Based on those numbers, very few tickets (if any) will be available on general sale in the spring.